报错背景：
CDH未关闭的情况下，Linux断电，导致cloudera-scm-server无法启动。
报错现象：
输入启动命令之后：/opt/cm-5.15.1/etc/init.d/cloudera-scm-server start，
cloudera-scm-server 会启动，但是几秒中之后就会死掉，显示：cloudera-scm-server 已死，但 pid 文件存在。
于是查看日志文件：vim /opt/cm-5.15.1/log/cloudera-scm-server/cloudera-scm-server.log，
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'com.cloudera.server.cmf.TrialState': Cannot resolve reference to bean 'entityManagerFactoryBean' while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactoryBean': FactoryBean threw exception on object creation; nested exception is javax.persistence.PersistenceException: org.hibernate.exception.GenericJDBCException: Could not open connection at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:328) at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:106) at org.springframework.beans.factory.support.ConstructorResolver.resolveConstructorArguments(ConstructorResolver.java:616) at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:148) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1003) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:907) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:485) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:293) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:290) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:192) at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:585) at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:895) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:425) at com.cloudera.server.cmf.Main.bootstrapSpringContext(Main.java:393) at com.cloudera.server.cmf.Main.<init>(Main.java:243) at com.cloudera.server.cmf.Main.main(Main.java:216) Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactoryBean': FactoryBean threw exception on object creation; nested exception is javax.persistence.PersistenceException: org.hibernate.exception.GenericJDBCException: Could not open connection at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.doGetObjectFromFactoryBean(FactoryBeanRegistrySupport.java:149) at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.getObjectFromFactoryBean(FactoryBeanRegistrySupport.java:102) at org.springframework.beans.factory.support.AbstractBeanFactory.getObjectForBeanInstance(AbstractBeanFactory.java:1440) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:247) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:192) at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:322) ... 17 more Caused by: javax.persistence.PersistenceException: org.hibernate.exception.GenericJDBCException: Could not open connection at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1387) at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1310) at org.hibernate.ejb.AbstractEntityManagerImpl.throwPersistenceException(AbstractEntityManagerImpl.java:1397) at org.hibernate.ejb.TransactionImpl.begin(TransactionImpl.java:62) at com.cloudera.enterprise.AbstractWrappedEntityManager.beginForRollbackAndReadonly(AbstractWrappedEntityManager.java:89) at com.cloudera.enterprise.dbutil.DbUtil.isInnoDbEnabled(DbUtil.java:554) at com.cloudera.server.cmf.bootstrap.EntityManagerFactoryBean.checkMysqlTableEngineType(EntityManagerFactoryBean.java:139) at com.cloudera.server.cmf.bootstrap.EntityManagerFactoryBean.getObject(EntityManagerFactoryBean.java:122) at com.cloudera.server.cmf.bootstrap.EntityManagerFactoryBean.getObject(EntityManagerFactoryBean.java:65) at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.doGetObjectFromFactoryBean(FactoryBeanRegistrySupport.java:142) ... 22 more Caused by: org.hibernate.exception.GenericJDBCException: Could not open connection at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:54) at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:125) at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:110) at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.obtainConnection(LogicalConnectionImpl.java:221) at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.getConnection(LogicalConnectionImpl.java:157) at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.doBegin(JdbcTransaction.java:67) at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.begin(AbstractTransactionImpl.java:160) at org.hibernate.internal.SessionImpl.beginTransaction(SessionImpl.java:1426) at org.hibernate.ejb.TransactionImpl.begin(TransactionImpl.java:59) ... 28 more Caused by: java.sql.SQLException: Connections could not be acquired from the underlying database! at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:118) at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:692) at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:140) at org.hibernate.service.jdbc.connections.internal.C3P0ConnectionProvider.getConnection(C3P0ConnectionProvider.java:84) at org.hibernate.internal.AbstractSessionImpl$NonContextualJdbcConnectionAccess.obtainConnection(AbstractSessionImpl.java:292) at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.obtainConnection(LogicalConnectionImpl.java:214) ... 33 more Caused by: com.mchange.v2.resourcepool.CannotAcquireResourceException: A ResourcePool could not acquire a resource from its primary factory or source. at com.mchange.v2.resourcepool.BasicResourcePool.awaitAvailable(BasicResourcePool.java:1469) at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:644) at com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:554) at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutAndMarkConnectionInUse(C3P0PooledConnectionPool.java:758) at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:685) ... 37 more Caused by: java.sql.SQLException: Access denied for user 'scm'@'master' (using password: YES) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:965) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3978) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3914) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:871) at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1714) at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1224) at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2199) at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2230) at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2025) at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:778) at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47) at sun.reflect.GeneratedConstructorAccessor5.newInstance(Unknown Source) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:423) at com.mysql.jdbc.Util.handleNewInstance(Util.java:425) at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:386) at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:330) at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:175) at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:220) at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:206) at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:203) at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1138) at com.mchange.v2.resourcepool.BasicResourcePool.doAcquireAndDecrementPendingAcquiresWithinLockOnSuccess(BasicResourcePool.java:1125) at com.mchange.v2.resourcepool.BasicResourcePool.access$700(BasicResourcePool.java:44) at com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask.run(BasicResourcePool.java:1870) at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:696)
报错原因：
日志里面写的很清楚，
原因：Access denied for user 'scm'@'master' (using password: YES)
翻译：用户“scm”@“主机”拒绝访问（使用密码：是）
为什么会拒绝访问呢？一头雾水啊！！！
分析以下，拒绝访问可能是没有权限访问，或者MySQL数据库没有启动。
首先排除MySQL数据库没有启动的原因，接下来就是寻找没有访问权限的原因了。
根据百度的结果，大部分造成此种结果的原因是没有提供MySQL的远程访问权限。
但是我很确定当时我已经设置了MySQL数据库开放远程访问权限。
走投无路，只能死马当作活马医了，重新开放权限。
报错解决：
[root@master sources]# mysql -uroot -proot
mysql> use mysql; mysql> select host,user,password from user; mysql> update user set password=password('root') where user='root'; mysql> grant all privileges on *.* to 'root'@'master' identified by 'root'; --'root'@'%'中 %代表所有主机
但是执行到上面这一步的时候又报错：
Access denied for user 'root'@'master' (using password: YES)
这次我是彻底懵逼了，为了解决权限的错误执行的命令竟然报出权限的错误。
在网上找了很长时间也没有找到解决方案，于是我只能重装数据库了。
重装完成数据库之后，再次执行赋予远程登录的权限就成功了。
mysql> use mysql; Reading table information for completion of table and column names You can turn off this feature to get a quicker startup with -A Database changed mysql> select host,user,password from user; +-----------+------+-------------------------------------------+ | host | user | password | +-----------+------+-------------------------------------------+ | localhost | root | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B | | master | root | *D2338747885A51AACEED4A7276143CB759A5B844 | | 127.0.0.1 | root | *D2338747885A51AACEED4A7276143CB759A5B844 | | ::1 | root | *D2338747885A51AACEED4A7276143CB759A5B844 | +-----------+------+-------------------------------------------+ 4 rows in set (0.00 sec) mysql> update user set password=password('root') where user='root'; Query OK, 3 rows affected (0.00 sec) Rows matched: 4 Changed: 3 Warnings: 0 mysql> grant all privileges on *.* to 'root'@'master' identified by 'root'; Query OK, 0 rows affected (0.00 sec) mysql> flush privileges; Query OK, 0 rows affected (0.00 sec) mysql> exit Bye
然后再执行数据库初始化
/opt/cm-5.15.1/share/cmf/schema/scm_prepare_database.sh mysql cm -hmaster -uroot -proot --scm-host master scm scm scm
参数分别是: 数据库类型 数据库名称 -h数据库主机名 -u数据库用户名 -p数据库密码--scm-host cmserver主机名 scm scm scm
主节点：通过/bigdata/cm-5.15.1/etc/init.d/cloudera-scm-server start启动服务端
[root@master /]# /opt/cm-5.15.1/etc/init.d/cloudera-scm-server start
这个时候cloudera-scm-server就不会挂掉了
